The present invention relates to stockpiling of flowable solid materials, such as coal, gravel, wheat, sand or the like, and more particularly to improvements in apparatus for accumulating and thereupon depleting stockpiles or heaps of such materials. Still more particularly, the invention relates to improvements in a method of and an apparatus for accumulating and simultaneously intermixing the ingredients of stockpiles consisting of flowable solid materials and for removing flowable materials from the thus accumulated stockpiles.
It is already known to accumulate flowable solid materials in the form of stockpiles or heaps wherein two halves of the accumulated material are mirror symmetrical to each other with reference to a vertical symmetry plane. Such stockpiles are often accumulated in the interior of a building, such as a shed, silo or hall.
Heretofore known techniques of accumulating stockpiles of coal, coke, grain, gravel, sand or like flowable solid materials include the so-called chevron process and the so-called windrow method. The chevron process can be practiced by resorting to a conveyor belt which extends above the crest and in the longitudinal direction of the stockpile and includes a looped portion serving to discharge flowable material while moving back and forth along an elongated path. The material which accumulates below the conveyor forms several layers which together form a stockpile resembling a gable roof. The ends of the stockpile have a semiconical shape. A drawback of the chevron process is that the stockpile cannot adequately fill a shed so that a relatively high percentage of the interior of the shed remains unoccupied, especially at the ends of the stockpile. Moreover, intermixing of the ingredients of the stockpile is unsatisfactory, especially at each end. Still further, it is difficult to remove material from the stockpile at a uniform or predictable rate, especially at the ends of the accumulated material.
The windrow method can be practiced by resorting to a conveyor which is adjacent to one side of the stockpile and supplies flowable solid material to a boom whose free end discharges thin piles of flowable material in the form of several parallel rows. Such rows form superimposed layers in that they are deposited next to as well as on top of each other. A mirror-symmetrical distribution of rows can be achieved by depositing a first row at one side of the imaginary symmetry plane which extends lengthwise of and halves the stockpile, by thereupon depositing a row at the other side of such plane, by again depositing a row at the one side of the plane, thereupon at the other side of the plane, and so forth. This necessitates changes in the effective length of the boom. The ends of a stockpile which is accumulated in accordance with the windrow method resemble semipyramidal bodies which is advantageous because such bodies are more likely to fill the corresponding ends of a shed or another structure in which the apparatus for accumulating the stockpile is installed. Furthermore, the windrow method ensures more satisfactory intermixing of the constituents at both ends of the stockpile as well as a more satisfactory or more predictable removal of material from the accumulated mass of granular, pulverulent or similarly configurated particles. However, the windrow method also exhibits several serious drawbacks. Thus, the boom requires additional space at one end of the stockpile because it must be fully extended over the accumulated material. Furthermore, the boom must be afforded room for pivotal movement, and the accumulation of a fully grown stockpile takes up a relatively long interval of time.